1. Field of the Invention
The present invention relates to an electrical connector provided with a locking mechanism. The electrical connector is used as an electrically connecting means for electric wires transmitting electric signals.
2. Description of the Related Art
In a certain kind of electrical connector, a housing thereof is provided with a lock arm. The lock arm swings like a seesaw. A locking part is provided in another housing of a mating connector. The lock arm detachably engages with the locking part. The electrical connector shown in from FIG. 17 to FIG. 23 belongs to this kind.
As shown in FIG. 17 and FIG. 18, in a conventional electrical connector 500, a lock arm 502 swingable like a seesaw is provided with an outer peripheral part of a housing 501. The lock arm 502 can engage with a locking part 602 provided with another housing 601 of a mating connector 600.
As shown in FIG. 19 and FIG. 20, a pair of side wall parts 504 and 504 are erected from an outer peripheral part 501a of the housing 501. The lock arm 502 is arranged between the pair of side wall parts 504 and 504. The lock arm 502 is connected to the outer peripheral part 501a of the housing 501 with a pair of leg parts 503. That is, the lock arm 502 and the housing 501 are integrally formed. The pair of leg parts 503 and 503 correspond to fulcrums of the lock arm 502. When the leg parts 503 and 503 are elastically bent, the lock arm 502 swings about the leg parts 503 and 503 utilizing thereof as fulcrums.
As shown in FIG. 18, when the electrical connector 500 and the mating connector 600, which are separated from each other, are moved in a coupling direction X to make them couple with each other, a locking part 502b of the lock arm 502 (of the electrical connector 500) abuts on the locking part 602 of the mating connector 600, and runs over it while sliding thereon. After that, the locking part 502b of the lock arm 502 fits into the reverse side of the locking part 602. In this way, the electrical connector 500 and the mating connector 600 are locked together.
As shown in FIG. 17, an operating part 502a of the lock arm 502 is located at a reverse side of the housing 501. The locking part 502b is located at a reverse side of the operating part 502a. As shown in FIG. 21 and FIG. 22, when the operating part 502a is pressed toward the housing 501, the lock arm 502 swings like a seesaw utilizing the pair of leg parts 503 and 503 as fulcrums. As a result, the locking part 502b moves in a direction away from the outer peripheral part 501a. If the pressing to the operating part 502a is released, the lock arm 502 returns to an original state (a state shown in FIG. 17 and FIG. 20) according to elastic restoring force of the leg parts 503 and 503.
When the electrical connector 500 and the mating connector 600 shown in FIG. 18 are coupled with each other and the operating part 502a of the lock arm 502 is pressed toward the housing 501, the locking part 502b is released (as shown in FIG. 21 and FIG. 22) from the outer peripheral part 501a of the housing 501, and the electrical connector 500 and the mating connector 600 can be separated from each other.
Reference 1 (Japan Registered Patent No. 3534013) and Reference 2 (Japanese patent application Laid-open on No. 2012-129077) disclose electrical connectors of the same kind.
A “connector” in Reference 1 is provided with a lock arm _40 swingable like a seesaw about a fulcrum part _42 similar to the lock arm 502 of the connector 500 shown in FIG. 17 (See, paragraph “0012” and FIG. 1 of Reference 1.).
Another “connector” in Reference 2 is also provided with a lock arm _34 including an arm body _36 swingable like a seesaw, or the like utilizing a leg part _35 as a fulcrum (See, paragraph “0020”, FIG. 3, and FIG. 4. of Reference 2).
There is demand for making the electrical connector as low as possible. In response to the demand, a method of shortening the leg parts 503 and 503 of the electrical connector 500 shown in FIG. 17 to approximate the lock arm 502 to the housing 501 may be taken in some cases.
Since the leg parts 503 and 503 work as fulcrums when the lock arm 502 swings, the bending moment concentrates on the leg parts 503 and 503. If the leg parts 503 and 503 are shortened, the leg parts 503 and 503 can be hardly bent and the load concentrates upon narrow regions of the leg parts 503 and 503 (especially, roots thereof). Therefore, stress concentration may easily cause plastic deformation of the leg parts 503 and 503.
As a result, the leg parts 503 and 503 cannot return to original positions thereof any more.
As shown in FIG. 23, the following phenomenon (so-called “settling of a lock arm”) may occur. That is, the leg parts 503 and 503 do not return to their original standing postures, and the lock arm 502 keeps inclined even after external force has been released. Once the “settling of the lock arm” has occurred, when the electrical connector 500 and the mating connector 600 are tried to connect to each other, locking therebetween must become imperfect. Unfortunately, the electrical connector 500 may come out from the mating connector 600 (See, FIG. 18).
It is predicted that such a phenomenon may occur in the same way according to the “connectors” of References 1 and 2. The conventional electrical connectors cannot resolve this problem.